Background and Study Aims:Conventional colonoscopy as the gold standard for large-bowel diagnostics and therapy may fail in 5%-20%of cases,depending on the experience of the examiner.Colonoscopy is regarded as difficult and painful by many patients.In an attempt to overcome the limitations of conventional colonoscopes,a guide wire-directed,thin,flexible diagnostic colonoscope,the CathCam was developed.In this prospective pilot study,we report its use in patients in whom conventional colonoscopy had failed.Patients and Methods:49 patients with a previous or current failure of complete colonoscopy were invited to participate in a trial using the new CathCam system,and 14(nine men;mean age 59 years)accepted.The CathCam is an 11-mm diameter disposable,multilumen catheter,with visualization by a 3-mm camera with six light-emitting diodes.In the first five patients,the CathCam was inserted over a newly developed 0.024-inch,hinged,lumen-seeking guide wire.Subsequently,a modified combined approach was used:a conventional colonoscope was introduced into the sigmoid or left colon,then the guide wire was advanced as far as possible,followed by CathCam insertion over it.Caecal intubation rate,insertion times and patient discomfort were recorded;patients received low-dose midazolam sedation(2-5 mg).Results:One patient was excluded during colonoscopy.The caecum could be eventually reached in 12 of 13 patients;in the remaining patient a significant sigmoid stricture could be passed,but further advancement appeared too risky.The mean caecal intubation time was 24 minutes(range 3-105 min).Only two patients experienced pain and discomfort during the procedure(one immediate assessment and one case reported at later telephone interview).No complications occurred,and previously undiagnosed important findings were obtained in 9 cases.Conclusions:A combined approach,consisting of guide wire insertion via a partially introduced colonoscope followed by CathCam or colonoscope insertion into the caecum was successful in over 90%of patients with previous failure of complete colonoscopy.Further improvements may make this system suitable for use as a standard diagnostic colonoscope,either as a single unit(CathCam plus guide wire)or using the guide wire alone with a standard colonoscope in difficult cases. Background and Study Aims: Conventional colonoscopy as the gold standard for large-bowel diagnostics and therapy may fail in 5% -20% of cases, depending on the experience of the examiner. Colonoscopy is viewed as difficult and painful by many patients. An attempt to overcome the limitations of conventional colonoscopes, a guide wire-directed, thin, flexible diagnostic colonoscope, the CathCam was developed. in this prospective pilot study, we report its use in patients in patients conventional colonoscopy had failed. Patients and Methods: 49 patients with previous or current failure of complete colonoscopy were invited to participate in a trial using the new CathCam system, and 14 (nine men; mean age 59 years) accepted.The CathCam is an 11-mm diameter disposable, multilumen catheter, with visualization by a 3-mm camera with six light-emitting diodes. the first five patients, the CathCam was inserted over a newly developed 0.024-inch, hinged, lumen-seeking guidewire. Subtructed, a modified combined appr oach was used: a conventional colonoscope was introduced into the sigmoid or left colon, then the guide wire was advanced as far as possible, followed by CathCam insertion over it.Caecal intubation rate, insertion times and patient discomfort were recorded; patients received low- Results: One patient was excluded during colonoscopy. The caecum could be eventually reached in 12 of 13 patients; in the remaining patient a significant sigmoid stricture could be passed, but further advancement had too risky. The mean caecal intubation time was 24 minutes (range 3-105 min) .Only two patients experienced pain and discomfort during the procedure (one immediate assessment and one case reported at later telephone interview) .Norges occurred, and previously undiagnosed important findings were obtained in 9 cases.Conclusions: A combined approach, consisting of guidewire insertion via a partially introduced colonoscope followed by CathCam or colonoscope insertion intothe caecum was successful in over 90% of patients with previous failure of complete colonoscopy. Further improvements may make this system suitable for use as a standard diagnostic colonoscope, either as a single unit (CathCam plus guide wire) or using the guide wire alone with a standard colonoscope in difficult cases.